The move towards self-driving cars is likely to be slow, because of the huge number of human-driven cars that are still on the road.

"I think it is important to appreciate the size of the automotive industrial base," Musk said. "There's 2 billion of them."

The switch to autonomous vehicles could take as long as 20 years, especially given the number of new cars that can be built is limited.

Musk’s electric car company, Tesla, has added some autonomous features to its cars — including the option to have cars keep themselves safe using an “autopilot” feature and built-in sensors. But fully self-driving vehicles are still far from being approved for the road, let alone taking over as the norm.

Musk was speaking at the conference because some of that work is being powered by Nvidia’s Tegra X1 chip, which was built in part specifically to power self-driving cars. The chip is small and powerful, and will help the company build the Drive PX platform the company is working on to help cars understand their environment as they drive through cities.

That kind of slow, city driving is the environment that self-driving cars have the most problems with, said Musk. When driving between 15 and 50 miles per hour, cars tend to run into unexpected things, like children in the road and diversions.